Gaseous photo-developing apparatus



2 Sheets-Sheet 1 V III III INVENTORS M. ELLIS P NEEB flTTOENEr' ROBERTROBERT BY R. M. ELLIS ETAL a Q Q Q 8 Q GASEOUS PHOTO-DEVELOPINGAPPARATUS March 3, 1964 Filed 001;.

R. M. ELLIS ETAL 3,122,981

GASEOUS PHOTO-DEVELOPING APPARATUS 2 Sheets-Sheet 2 March 3, 1964 FiledOct. 20,1961

INVENTO ROBERT M R0 as RT HTTORNEY United States Patent 3,122,981GASEOUS PHOTO-DEVELGPING APPARATUS Robert M. Ellis, Basking Ridge, andRobert P. Neel), Franklin Park, N J assignors to Rotolite Corporation,Stirling, N1, a corporation of New Jersey Filed Get. 20, 1961, Ser. No.146,510 1 Claim. (Cl. 95-94) The invention relates to photo-copyingduplicators or printing apparatus of the type wherein photo-sensitivesheets of base material (generally paper)-having in one face aphotosensitive emulsion coating of the diazo typeare, after exposure, tobe treated with ammonia water vapor for the development of the latentimage. It is directed more especially to novel apparatus for elfectingsuch development by the vapor as generated from ammonium hydroxide orthe like. Coated paper commonly used in the reproduction of engineeringdrawings, business papers and the like, may readily be processed in saidapparatus, such papers being referred to, generally, as of the diazo"type which produce right-reading copiesthe reproduced image being of acolor depending upon the particular diazo compound utilized.

In operating with this type of paper in conventional machines, the lightpassing through a more or less translucent original to the sensitized(coated) copy sheet will then burn off the sensitized coating in passingthrough such original. The dark or opaque portion, however, will notpermit light passage and thus prevents such burn off. Upon subsequentdevelopment or exposure then to, for example, ammonia vapors, an exactcopy of the original is reproduced.

Apparatus for carrying out of the development of the aforesaid prints,comprises, generally, means for effecting association temporarily of asource of ammonia gas with a means for advancing an exposedphoto-sensitive sheet for subjection to said gas.

Broadly, it is an object of the present invention to provide a novel,simplified, trouble-free and inexpensive construction of suchapparatus-more especially in relation to the delivery of the gaseousmedium (ammonia vapor) to a previously exposed, sensitized sheet astraveled through a portion of the apparatus, said sheet then beingdirectly associated with the said gaseous medium.

An important object of the invention, also, is to effect the saiddeveloping operation without incurring moisture condensation problemsprevalent in currently used apparatus of this nature.

Another object of the invention is to provide apparatus of the aforesaidnature whereby operation will be facilitated, more especially withrespect to the contact relationship of the light-exposed, sensitizedsheet with a selected developing agent-generally gaseous ammonia vapor;also, to the provision of apparatus which lends itself to operationeither in a table top or in a wall mounted position.

A still further object of the invention is to provide, for use in suchapparatus, a trouble-free ammonia feed; and one with which objectionablevolumes of ammonia vapor are prevented from escaping to the surroundingatmosphere.

The invention contemplates, moreover, the provision of a novel means forapplying heat to the developing agent during operation of development;and, also means for minimizing the development of moisture condensationin areas where such condensation could contact and stain the sensitizedsheet being developed.

In carrying out the invention-it being noted that diazo type coatingsare available in various colors and combinations thereof, and that someheat and moisture should be present in the developing agent to developadequately the full range of colors-the ammonia gas is associated with"ice the said diazo type material through perforations in a flexibleslip-screen.

Between this screen and an associated tubular roller, the sensitizedpaper is then advanceda substantial area of the perforated portion ofsaid screen being arranged for contact with the periphery of said rollerin the advance of copy by the latter. The said roller thus substantiallyseals outward flow, through the perforations, of ammonia gas; and thusserves to obviate excessive leakage thereof externally of the apparatus.Such apparatus is otherwise to be sealed olf from ammonia gas supplythesaid screen in some portion of the contact area and beyond beingimperforate.

Furthermore, a novel arrangement whereby to furnish heat is, inaccordance with the invention, to be associated with the aforesaidroller at a location where it will be most effective and will, also,obviate problems of moisture condensation on the prints.

In accordance with common practice, the location of an ammoniumhydroxide retaining vessel should be at the hottest section of theammonia chamber. However, this results in vapor condensation at areaswhere high temperatures cannot ordinarily be maintained-particularlywhere constant passage of papers tends to reduce the tem perature of thesurrounding structure. It is common practice, also, to correct suchcondition by the installation of additional, strategically locatedheaters. The location of a perforated exposure surf-ace also may bearranged at the upper portions of an ammonia chamber so that vaporcondensate will tend to fall away and thus avoid staining of thesensitized surface of a print-as would result from wetting of the same.In the case of the novel construction, however, the heat is appliedsolely to the said associated roller, and at a point external to thegaseous cham ber associated therewith. Such application of heat willthen produce maximum molecular activity of the gaseous medium as appliedto the paper fed over the surface of said heated roller.

The nature of the invention, however, will best be understood whendescribed in connection with the accompanying drawings, in which:

FIG. 1 is a front elevation of the novel photo-developing apparatus.

FIG. 2 is a horizontal section therethrough, taken on the line 22, FIG.1 of the drawings, and looking in the direction of the arrows.

FIG. 3 is a transverse section on an enlarged scale, taken on the line33, FIG. 1, and looking in the direction of the arrows.

FIG. 4 is a fragmentary, longitudinal section, on an enlarged scale,taken on the line 44, FIG. 2, and looking in the direction of thearrows.

Referring to the drawings, the novel photo-developing apparatuscomprises a suitable supporting base in the form, for example, of abox-like structure 10 which supports preferably a switch 11 at the rearfor electric control of the developing operation, as will hereinafter bemore fully set forth. Along the paper-discharge (rear) side, thebox-like unit may be provided with an outwardly-extending flange 12having key-hole slots 13 whereby to suspend for operation the unit in avertical or wall-hanging position.

To the top of the box 10 there is attached an inwardly inclined guidestrip 14 for guiding exposed prints to the one side of theammonia-applying region, as will here inafter be more fully set forth.Similarly, along the opposite side, there is secured a discharge strip15-said strips cooperating with corresponding inturned wall portions 14,15 of a gas-retaining housing 16 to afford respective inlet, outletchannels for a print 17, respectively a a to and from an intermediatefeed roller 18 which is supported on an operating shaft 19.

Mounting of the gas-retaining housing 16 on the aforesaid box-likestructure 10, moreover, is such that it is possible to apply suitabletension to a perforated, arcuate strap or slip-screen 29 which servesthen to close the gap between the inturned portions 15 of the saidhousing 16. The latter to this end is supported pivotally along therear, as upon brackets 21; and there are provided at the front inwardlyturned and threaded brackets 22 designed to receive adjusting screws 23passing freely through the top of the box-like structure 1tl-re spectivesprings 24 being introduced between said structure and the correspondinghead of a screw. The mounting is such that the required tensiontominimize leakage of gas through the perforations of the screen or strapduring operationis readily attainable by correspondingly adjusting thescrews 23.

The said slip screen or strap 20 thus is formed over an open section ofthe bottom of the gas-retaining housing 16 as a transverse, flexible andmore or less semicircular section or strap portion which conforms to andfits snugly then over a portion of the surface of roller 18. Thissection of the slip screen between which and the periphery of saidroller a print is designed to pass upon rotation of said roller, is of amore or less flexible material such as Teflon; and is perforatedsubstantially over the contacting area, such that ammonia fumes willthen pass readily therethrough to act, however, only on a passing,underlying print for the development of its previously exposed emulsionportion, as is Well understood.

Moreover, such contact strap portion should be composed of a materialhaving a very low coefficient of friction, for example, so as to be heldin a close-fitting wrap part of the way (approximately 145) around theheated roll surface and still permit papers being developed to move withthe surface of the roller, which has a relatively higher coelficient offriction, as it rotates about its axis.

The partially perforated strap, the cover and its turnedin portions 14and 15' together with the closely fitted end walls 16', 16" thus form asealed gas chamber except for'the perforations of the slip screen.Ammonia vapor is always available on the surface of the roller throughthe perforations but in efiect is wiped off and returned to the chamberas the smooth surface of the roller passes each perforation. Ammoniavapor is also available in the same manner with respectto papers passingthrough the developing area, but is absorbed into the relatively poroussheet in quantities suficient to effect development of the diazochemicalsexcessive vapors being wiped off as hereinbefore described.The-only vapor to pass out of the apparatus is that whichis carriedbythe structure of the paper itself.

The ammonia vapor for such development is continuously to be supplied tothe interior of the housing 16, as from an insertable, tubular trayelement 25 which is sealed at its inner end and is designed to retain acharge of the ammonium hydroxide. To this end, the said tray element isprovided with an upper, longitudinal discharge opening 26 which is,preferably, extended more or less laterally and along the said tubulartray to an appreciable dimension within the sealed gas chamber. The saidopening 26 thus permits free vaporization of ammonium hydroxide into thechamber; and its angular position allows of the filling (partial) of thetray with the ammonium hydroxide when the printing apparatus is utilizedeither in a horizontal (table top) or a vertical (wall hanging)operating position. The said tray element 25 projects, at its fillingend, slightly beyond the housing 16; and it is connected, through anintermediate reduced sleeve portion 27, to an end fitting 28 which isprovided with the filling opening 29. The said fitting serves then notonly as a means of filling and draining of the tray; but, if saidfitting be constructed of transparent material, will serve as well as aliquid level gage.

A set screw 31), fitting a peripheral groove 31 in the outer, reducedend of the said tray element 25, may serve to lock said fitting againstlongitudinal displacementthe former being sealed rotatably tothe tryelement by means of an 0 ring 32.

To effectthe heating of the roller during operation, the one end of thesaid roller is equipped with a rotatable slip ring 33 for supply ofelectric current from leads 33 to a loop 34 of resistance Wire. Thelatter is helically wound about the shaft 19, the power supply beingunder control of the switch 11 which supplies, also, power to a motor 35for effecting rotation of the said roller 18, as well as a fan 36.

The exposed sheet thus advanced becomes heated between the rollersurface and the slip screen, thereby materially increasing the molecularactivity of the said gaseous agent which results in a substantiallyincreased production rate.

We claim:

Apparatus for the production of photo-mechanical prints on diazo-typepapers, comprising: a base, and a housing mounted thereon affording anelongated, ammonia-retaining exposure chamber with elongated bottomopening; a resilient strip of non-porous material secured over saidopening, inwardly directed into said chamber and having an arcuatesection thereof perforated for discharge of ammonia gas directly to thesurface of an inserted sheet; a roller external-1y contacting the saidperforated area thereof as Well as non-perforated portion beyond thesame, said non-perforated portions sealing the exposure chamber againstleakage; and an operative shaft for said roller, extending externally ofthe housing, to effect its rotation and to advance thereby an exposedprint to the contacting area wherein the ammonia exposure chambercontains an externally scalable ammonia supply tray whichis mountedtherein and provided with a longitudinal opening so arranged as todisehargegas into the exposure chamber when the apparatus is used ineither its horizontal or vertical operating position.

References Cited in the file of this patent UNITED STATES PATENTSFOREIGN PATENTS 462,971 Great Britain Mar. 18, 1937

